This invention relates generally to devices for filling a gas-pressurized liquid into containers and more particularly it relates to a device for filling CO.sub.2 -containing beverages into containers, the device having a vertically movable air-return pipe adapted for movement into a filling position in which it partially enters the container to determine the maximum filling level, and into an elevated position above the container to permit the exchange of the container.
A filling device of the above-described type is known from the German Pat. No. 1,174,196. In the construction according to this patent, the filling devices are situated at the bottom of a filling tank storing the gas-pressurized liquid. The air-return pipe of each filling device is slidably supported for a reciprocating vertical movement and projects upwardly through the head part of the filling device as far as to the gas-filled upper space of the tank. High filling pressures in the counterpressure filling devices of this type do not cause any substantial sealing problems due to the fact that the interior of the filling device and the interior of the filling tank are subject to the same pressure in most stages of the filling operation. Also the connection of the open end of the air-return pipe with the gas-filled space of the tank for producing the initial pressure and for returning the air in the container presents in this construction no problems.
Filling devices of the above-described type which are arranged off the bottom of the filling tank have been devised in the British patent specification No. 371,498. The filling device itself has substantially the identical structure as that of the aforementioned German patent, but the free upper end of the air-return pipe projects through the head of the filling device into the free atmosphere and the movement of the pipe is derived from a direct drive, for example by means of lifting cams. The connection to the pressurized gas is effected via flexible conduits acting on the air-return pipe or via a shiftable connection in the head of the filling device. The disadvantage of this solution is the necessity to provide sliding seals for the air-return pipe which in the case of high filling pressures such as 6 Bars, for example, are prone to wear. In addition, the gas connection to the air-return pipe is complicated and its structure is expensive and demanding on maintenance.